Because of possible carcinogens. https://popculture.com/trending/new...jjuNv7dqWJQos2AZ3HGtplBG7dpa-dBW0Pg4BA2kFzj04
Aerosol only due to the benzene not only being a carcinogen, but flammable. I've been using Brut Classic antiperspirant / deodorant stick for years. Best stuff I've found. I can soak a T-shirt and the pits will still be dry.